Key Vocabulary: Penis- The male organ of copulation and, in mammals, of urinary excretion. Vagina- the passage leading from the uterus to the vulva in certain female mammals. Prostate- A gland in male mammals that surrounds the neck of the bladder and urethra and secretes a liquid constituent of the semen.

Did You Know?:There are approximately 5 calories in a teaspoon of semen.